Index: django/forms/formsets.py
===================================================================
--- django/forms/formsets.py	(revision 9067)
+++ django/forms/formsets.py	(working copy)
@@ -273,9 +273,9 @@
         return mark_safe(u'\n'.join([unicode(self.management_form), forms]))
 
 def formset_factory(form, formset=BaseFormSet, extra=1, can_order=False,
-                    can_delete=False, max_num=0):
+                    can_delete=False, max_num=0, classes=[]):
     """Return a FormSet for the given form class."""
-    attrs = {'form': form, 'extra': extra,
+    attrs = {'form': form, 'extra': extra, 'classes': classes,
              'can_order': can_order, 'can_delete': can_delete,
              'max_num': max_num}
     return type(form.__name__ + 'FormSet', (formset,), attrs)
Index: django/forms/models.py
===================================================================
--- django/forms/models.py	(revision 9067)
+++ django/forms/models.py	(working copy)
@@ -418,7 +418,7 @@
         super(BaseModelFormSet, self).add_fields(form, index)
 
 def modelformset_factory(model, form=ModelForm, formfield_callback=lambda f: f.formfield(),
-                         formset=BaseModelFormSet,
+                         formset=BaseModelFormSet, classes=[],
                          extra=1, can_delete=False, can_order=False,
                          max_num=0, fields=None, exclude=None):
     """
@@ -427,7 +427,8 @@
     form = modelform_factory(model, form=form, fields=fields, exclude=exclude,
                              formfield_callback=formfield_callback)
     FormSet = formset_factory(form, formset, extra=extra, max_num=max_num,
-                              can_order=can_order, can_delete=can_delete)
+                              can_order=can_order, can_delete=can_delete,
+                              classes=classes)
     FormSet.model = model
     return FormSet
 
@@ -514,7 +515,7 @@
 
 def inlineformset_factory(parent_model, model, form=ModelForm,
                           formset=BaseInlineFormSet, fk_name=None,
-                          fields=None, exclude=None,
+                          fields=None, exclude=None, classes=[],
                           extra=3, can_order=False, can_delete=True, max_num=0,
                           formfield_callback=lambda f: f.formfield()):
     """
@@ -541,6 +542,7 @@
         'fields': fields,
         'exclude': exclude,
         'max_num': max_num,
+        'classes': classes,
     }
     FormSet = modelformset_factory(model, **kwargs)
     FormSet.fk = fk
Index: django/contrib/admin/options.py
===================================================================
--- django/contrib/admin/options.py	(revision 9067)
+++ django/contrib/admin/options.py	(working copy)
@@ -750,6 +750,7 @@
     template = None
     verbose_name = None
     verbose_name_plural = None
+    classes = []
 
     def __init__(self, parent_model, admin_site):
         self.admin_site = admin_site
@@ -790,6 +791,7 @@
             "formfield_callback": self.formfield_for_dbfield,
             "extra": self.extra,
             "max_num": self.max_num,
+            "classes": self.classes,
         }
         defaults.update(kwargs)
         return inlineformset_factory(self.parent_model, self.model, **defaults)
Index: django/contrib/admin/templates/admin/edit_inline/stacked.html
===================================================================
--- django/contrib/admin/templates/admin/edit_inline/stacked.html	(revision 9067)
+++ django/contrib/admin/templates/admin/edit_inline/stacked.html	(working copy)
@@ -1,5 +1,6 @@
 {% load i18n %}
 <div class="inline-group">
+<fieldset class="module {% for class in inline_admin_formset.formset.classes %}{{class}}{% endfor %}">
   <h2>{{ inline_admin_formset.opts.verbose_name_plural|title }}</h2>
 {{ inline_admin_formset.formset.management_form }}
 {{ inline_admin_formset.formset.non_form_errors }}
@@ -24,3 +25,4 @@
 {#   <li><a class="add" href="">Add another {{ inline_admin_formset.opts.verbose_name|title }}</a></li> #}
 {# </ul> #}
 </div>
+</div>
Index: django/contrib/admin/templates/admin/edit_inline/tabular.html
===================================================================
--- django/contrib/admin/templates/admin/edit_inline/tabular.html	(revision 9067)
+++ django/contrib/admin/templates/admin/edit_inline/tabular.html	(working copy)
@@ -2,7 +2,7 @@
 <div class="inline-group">
   <div class="tabular inline-related {% if forloop.last %}last-related{% endif %}">
 {{ inline_admin_formset.formset.management_form }}
-<fieldset class="module">
+<fieldset class="module {% for class in inline_admin_formset.formset.classes %}{{class}}{% endfor %}">
    <h2>{{ inline_admin_formset.opts.verbose_name_plural|capfirst }}</h2>
    {{ inline_admin_formset.formset.non_form_errors }}
    <table>